Vibrating screen



' April 29, 1941. H, 1 coRwlN VIBRATING SCREEN Filed April 10, 1959 5 Sheets-Sheet 2 April 29, 1941. H. L. co'RwlN VIBRTING SCREEN Filed 'April 1o, 1939 5 Sheets-Sheet 3 will , Lee Cor ed on the sub-trame,

Patente r..

Vernon 'llooi Co. Ltd., Los f poration oil California Application April l0, i030, Serial No. 267.04m

This invention relates generally to vibrating screens, and more particularly to vibrating screens of the type wherein a vibrating screen frame is mounted in resilient supports. The'invention is concerned particularly with a type o screen employed in oil iield operations to separate "rotary mud from sand and cuttings, andwill be particularly described with that application principally in View, but without implied limitation thereto since the invention is equally adaptable to various other classes of vibratory screens.

'I'he present invention may be regarded as an improvement in a. type of screen in whch a vlbratory screen frame, which carries a rotating eccentric weight, is mounted on resilient supports, such as rubber blocks. In a prior screen of this type, four of such blocks are used near the four corners of a substantially rectangular screen frame, and are mounted directly on a stationary sub-frame. I Speaking generally, the greater the speed of rotation of the eccentric weight, the greater, of course, is the vibratory action of the frame and the effectiveness of screening. However, panied by increased strain on the machine, which is severe at best,l and in practice a speed of approximately 3400 R. P. M. is about the maximum consistent with safety to the machine, unless constructed of unduly heavy materials.

A general object of the invention is to provide an improved vibratory screen of lthe general type mentioned, characterized by increased amplitude of vibratory action without increase in the Speed of rotation of the eccentric weight.

A more particular object is to provide an improved mounting for the vibratory screen which will increase the vibratory freedom o the screen and will increase the amplitude of vibration, particularly the vertical component, or component normal to the screen surface.

In accordance with a preferred form of the present invention, the screen frame, with. its unbalanced rotating shaft, is mounted on av pair of resilient supports, preferably live rubber blocks, which support the screen frame at pointslocated in a vertical plane passing substantially or approximately through or near the center of gravity increased speed is accom of the vibrating screen assembly, this plane l: .i

to one side of .the unbal preferred form of the inblocks are carried by upwliich are pivotally mountin such manner that the screen-frame is supported for tree doa movement in a horizontal preferably somewhat anoed shaft. In the vention, these rubber standing rocker arms,

or longitudinal direction.,l

c ill eles, Calii., a cor- Another pair of resilient supports, also preferably live rubber blocks, support the screen-frame at points horizontally spaced from the iirst mentioned blocks, and on the side of the center of gravity opposite to that on which the unbalanced shaft is located, these latter resilient supports being mounted directly on the subframe. In result, the flexibility of the screen-frame mounting, and the vibration amplitude of the screenframe, are very materially increased.

It is of course obvious that the slower the machine can be operated, the less will the strain be on bearings and vibrating frame, and the less will be maintenance troubles. One practical embodiment of the particular type oi prior art machine reerred to has a working speed of between 3000 and 34000 R. l?. M., .any speed substantially above 34:00 R. P. M. placing too great a strain on the mechanism for safety, while the machine is inelcient below 3000 R. P. M. The same machine, but with one pair oi the resilient mountings moved to a position in vertical alinement with the center of gravity of the vibratory-screen, and also placed on rochers, has its optimum perormance within the range 'oi 2600 to 2800 R. P. M.-a material reductionwhile at the same time the amplitude of vibration is substantially doubled. Thus the present invention results in substantially greater vibration amplitude at substantially lesser speed, and practical machinesv Fig. 2 is a vertical section on line 2-2 of Fig.` showing one of .the screen-frame mountings;

Fig. 3 is a section taken on line t-d ofFlg. 1, showing another of Fig. 'i is a plan view of the machine;

Fig. 5 is a section taken on line 5 5 of Fig. 4;

Fig. 6 is a section taken as indicated by line t-t of Fig. 5;

Fig. 'l is a view taken as indicated by arrows l-i on Fig. 5; and

Fig. 8' is a section taken as d-d of Fig. 7.

In the drawings, which show a typical illustrative embodiment of the invention, numeral ld designates generally the vibratory screen-frame,

indicated by line the screen-frame mountings; A

Y port the wire screen 5|,

and numeral designates generally a suitable sub-frame or base. The latter includes parallel longitudinally extending skids I2, connected by forward and rearward tubular transverse members I3. At the sides of the machine, directly over skids I2, are inclined angle members I5, which are supported at their rearward or elevated ends by angle members I6 rising from skids I2, at points intermediate of their lengths by angle members I1 rising from skids I2, and at points near their forward ends by a plate I8 welded between the opposed anges of transverse angle members I9 and 20, which latter are welded to angle members I5 and skids I 2, respectively. Transverse, horizontal angle members 2I| and 22 extend between and are welded to rearward angles I6 to brace the machine'at the rearward end and' provide support for certain members later to be mentioned.

Within frame work ||v as described, and below screen frame I0, is a collection chamber 30 for materials passed through the screen, the chamber being dened by bottom wall 3|, side walls 32 and 33, rear wall 34, and front wall 35. A discharge trough 36 opens through side wall 32.

'I'he aforementioned screen-frame I0 is vcom-- prised of side plates 40 and a central longitudinal partition 4 I joined at the rear by transverse angle member 43 welded to members 40 and 4|, and at the front by a welded transverse member 44. The screen-frame is further braced by transverse tubular members 45-extending between and welded to side plates 40 and passing through notches 46 in the lower ledge of partition 4| (see Figs. 5 and 6).

Arranged transversely of frame I on each side of partition 4I is a plurality of transverse screen supporting members 50, of angle section. The upper edges of these members 50 carry rubber moldings or guards 59a which engage and supand the members are so disposed as to support screen in a downwardly inclined and curved position, as illustrated in Fig. 5. 'Ihe rearwardl edge of screen 5| is hooked to the rearwardly projecting flange of angle member 43, as indicated at 52, while the forward edge of the screen is hooked over a bar 55 welded to a rotatably adjustable tube 56, in the manner clearly indicated at 55a in Fig. 8. In the particular construction illustrated, there are two screen members, one on each side of center Apartition 4|, and each of these is secured to abar 55 mounted on a rotatable tube 56. The ends of tubes 56 adjacent partition 4I are rotatably mounted on studs 51 welded to partition dll (see Fig. 7), while the other ends of the tubes are secured and supported by clamps 60 secured 'in position by screws 6I. The ends of the tubes adjacent partition 4| are secured against rotation lby means of set screws 63 engageable against `studs 51 (see Fig. 7). 'I'he screens are tensioned by rotation of tubes 56, which are then secured in tensioning position by setting up screws 5| and 63. 1

Extending transversely between the upper por'- tions of side plates 40, and at a position preferably approximately two-thirds of the frame length from the rearward or feed end thereof is a channel member 10, which is further' braced by transverse members 1|, members 10 and 1| being secured rigidly to plates 40 and 4| as by welding. Mounted on the upper side of channel member are bearings 13 and 14 for opposite ends of a rotatable shaft 15. The latter being provided with eccentric weight 16. A guard 11 member 10 encloses shaft 13 and 14. A pulley 18 on by belts 19 to a pulley 80 on the shaft 8| of an electric drive motor 92. 'I'his motor 82 is supported by any suitable supporting structure 83 extending upwardly from the sub-frame at one side of vibrating screenframe I0. Unbalanced shaft 15, mounted as described, is thus located on the upper portion of the screen, and in a position preferably approximately two-thirds of the way from the feed to the discharge end of the screen, though it is to be understood the exact position is subject to some modification. Preferably, however, shaft 15 is so located that it is forwardly of the center of gravity of the screen frame, or in other words, to the right of the center of gravity as viewed in Fig. 1, the vertical plane in which the center of gravity of the screen frame and parts mounted thereon is located being represented by the dot-dash line V.

The materials to be screened are fed to the rearward, upper portion of the screen from a delivery trough generally indicated at 85, the latter being shown in Figs. 1 and 5 to be supported by suitablebracing 86 extending from frame member 22, and also by frame member 2| (see Fig. 5). An adjustable gate 81 spreads the material uniformly over the screen.

There remains for description the resilient mounting of the vibratory screen-frame on subframe II. In the illustrative and preferred embodiment of the invention, this resilient mounting comprises four live rubber blocks, two of which, designated at 90, are rigidly mounted on the sub-frame and support the vibratory screenframe I0 near or at its upper or feed end, and two of which, designated at 9|, are mounted for free-oating movement in a direction longitudisecured to channel 15 between bearings shaft 15 is connected nally of the screen-frame, being preferablyl rocker-mounted on the sub-frame. and support vibratory frame I0 at points in a vertical plane which passes substantially through the center of gravity of the vibratory assembly. The vibratory assembly may be defined as vibratory frame I0 and-all parts mounted thereon, including rotating shaft 'l5 and eccentric weights 16.

In the specific construction here illustrated, rubber blocks 90 and 9| are circular in formation and peripherally engaged by and encased within mounting castings 92. The blocks have bores 93 receiving tubular member 95, preferably slightly conical, mounted on tubular studs 91 furnished with mounting flanges 98 secured, as by bolts 99, to screen frame side plates 40. The inner ends of tubular members have annular flanges 96, which engage and confine the inner surfaces oi the rubber blocks.

.'Ihe mountingcastings 92 for blocks 90 have base flanges I0| secured by bolts |02 directly to the horizontal flanges |5a of the aforementioned angle members I5 forming a Dart of the rigid sub'- frame. The mounting castings 92 for blocks 9| are provided with'similar base flanges I0| secured as by bolts |02 to the upper portions of upstanding rocker arms |05 (Figs. 1 and 2). the latter being pivotally mounted at vtheir lower ends ou studs |05'carried by bearings or supports |01 sel said, the center of gravity of screen-frame lil, to-

gether with all its appurtenances including the vibrator constituted by theY eccentric weighted or unbalanced shaft, is substantially in the same vertical plane with the centers of blocks 3l and the pivot axis of rockers |05, whilethe unbalanced shaft l5 is offset somewhat forwardly from this plane. The weight of the vibrating assembly is accordingly carried substantially exclusively by rocker-mounted rubber blocks 9i. Rubber blocks Q0, supporting the vibrating frame at points spaced horizontally from blocks tl, therefore do not bear any substantial part of the weight of the vibratory frame. Accordingly,'whereas the lower portions of rubber blocks 9i are normally under substantial compression, blocks 9@ are not normally under substantial compression. This condition results in materially increased freedom and capability for vibration of frame lil, when the eccentric weighted shaft is set into rotation. In particular, the positioning of one pair of the resilient supports in approximately the vertical plane of the center of gravity increases the freedom for vertical movement, or for rocking action about the centers of said supports, while the arranging of said supports for free `floatinghorizontal travel, here typically shown as accomplished through use of the described rocker mountings, increases the freedom for horizontal movement. It will be evident that the nearer the points of support of the shaker frame by blocks lll are to the vertical plane passing through the center of gravity of the shaker frame and unbal- ,ily apparent.

(forward) end portion of the screen frame describes, typically, a somewhat elliptical path, with its major axis approximately vertical, the minor axis of the ellipse being proportionately somewhat greater than for the ellipse at the feed end of the frame. For a typical embodiment of the invention, the elliptical path at the feed end of the trame is of a length of approximately from 33e to 3%" or greater, depending upon the speed and the individual characteristics of the machine tested, while the horizontal component of vibration depends upon the length and also the inclination of the long axis of the'elliptical path with reference to horizontal, as will be read- The horizontal component is ample under the running conditions described. The elliptlcal path at the forward end portionof the frame, on the other hand, has, typically, a substantially, vertical major axis, and therefore a' vertical component of travel, of a length of from Tie" to aas". The horizontal component at the forward end portion of the frame ranges typicallyefrom two-thirds to nearly equal to the vertical component, again depending upon certain factors which are variable in operation and construction.

The machine as described thus provides materially increased amplitude of vibration, in both anced shaft, theA greater will be the proportion of the weight of the shaker frame and unbalanced shaft borne by blocks @if and therefore the greater will be` the freedom for the described vibratory action; however, any approach of blocks @l toward the center of gravity of the shaker frame and unbalanced shaft, so as to place the load more greatly on blocks Si than'on bloclrs all, will increase the freedom for the described vibratory action in accordance with the principles of the present invention, particularly when the blocks 9i, or their equivalent, are supported for comparatively free-floating horizontal movement, or movement longitudinal of the shaker frame. At the same time the location-of unbalanced shaft at a position offset in a forward direction from the vertical plane which includes the centers of action of the rocker mountings induces a rocking action of the screen frame about said centers. These features greatly free the screen frame for the required vibratory action. This increasedfreedom 'may readily be observed when the unbalanced shaft is at rest, simplyby manually shaking the frame;

In operation, unbalanced shaft 'i5 is driven in a right-handed direction, as viewed in Fig. 5, and for a typical embodiment of the invention, the appropriate speed of rotation for optimum screening performance ranges from 2500 to 2800 R. P. M. Under such conditions the entire screen frame is set into high amplitude vibration. A given point on the rearward or feed end 'of the screen frame describes, typically, a comparatively flat elliptical path, the major axis of which may be vertical, or tilted away from the feed end of the screen to an angle up to approximately depending somewhat upon the speed of the machine. Typically, the ellipse is vertical at a speed of approximately 25100 R. P. M., and becomes tilted to a 45 angle at about 2600 R. P. remaining at the latter angle for speedsgreater than 2600 R. l?. M. A given point on the other vertical and horizontal directions, while operating at reduced speed. The effectiveness of the screening action is therefore materially increased, while owing to decreased speed of the machine, wear on the bearings and breakage of parts is materially decreased.

It is to be understood that while I have here shown a typical embodiment of my invention, this is for illustrative purposes only, and that various changes in design, structure and arrangel ment may be made without departing from the spirit and scope of the invention or of the appended claims.

I claim:

l. A vibratory screen comprising, a vibratory screen frame having a longitudinally extending v screen fabric, a vibrator mounted on Said screen frame, a stationary frame, a pairof universally resilient supporting elements connected with opposite side portions of said vibratory screen frame at points approximately in a vertical plane that passes through the center of gravity of said screen frame and vibrator, means supporting said supporting elements on said stationary frame for free-floating substantially horizontal movement in a, direction longitudinally of the screen frame, said means comprising a pair of substantially vertical .rocker arms pivotally mounted on thev stationary frame and supporting said supporting elements at their free ends, and another pair of universally resilient supporting elements supported by said stationary frame and connected with said vibratory frame at points horizontally spaced from said center of gravity in a direction longitudinally of the vibratory screen frame.

2. s. vibratory screen comprising, a vibratory screen frame having a longitudinally extending screen fabric, a vibrator mounted on said screen frame, a stationary frame, a pair of universally resilient supporting elements connected with opposite side portions of said vibratory screen frame at points approximately in a, vertical plane that passes through the center of. gravity of said screen frame and vibrator, means supporting movement in a, direction longitudinally of the screen frame, said means comprising a pair of Zontally spaced from said center of at their free ends, and another .versally resilient supporting elements supported tion longitudinally ofl rotation of said ing said supports at mounted on seid stationary frame and supporting said vibratcry screen frame at a position hongravity and near one endet the screen frame.

3. A vibratory screen comprising, a vibratory screen frame having a longitudinally extending -screen fabric, a vibrator mounted on said screen frame, a stationary trame, a pair of universally .resilient supporting elements connected with opposite side portions of said vibratory screen frame, means supporting said supporting elements on said stationary frame for freeerl-oatins substantially horizontal movement in a direction 'longitudinally of the screen frame, said means comprising a pair of substantialiy vertical rocker armspivotaliy mounted on the stationary frame and supporting said supporting elements pair of unipy said stationary frame and connected with said vibratory frame atpoints horizontally spaced from said rst mentioned supporting elements in a direction longitudinally of the vlbratory screen frame 4. A vibratory screen comprising, a vibratory screen framehaving a longitudinally extending screen fabric, a vibrator mounted on said screen frame, Aa stationary frame, a pair of universally resilient supporting elements connected with opposite side portions of said vlbratory screen frame, means supporting said supporting ele-J ments on said stationary frame substantially horizonte longitudinally' of the screen frame, said means comprising a pair of substantially vertical rocker arms pivotally mounted on the stationary frame and supportingsaid supporting elements'at their free ends. 'and additional resilient supporting for free-floating movement in a'direction aasaces i resilient supports from the means mounted directly on said stationary frame l and connected with said vibratory screen frame at 'a position horizontally spaced from said uni verselly resilient supporting elements in a direc'- of the vlbratory screen frame.

5. A vibratory screen comprising, a screen frame having a feed end and a discharge end and provided with a longitudinally extending screen fabric, an unbalanced shaft rotatably mounted on said screen frame in' a transversely extending position, the center of gravity of said screen frame and unbalanced shaft lying in a vertical plane horizontally odset from the'center unbalanced shaft, a pair of resilient supports engaging opposite 'side portions of said screen frame at points located near said vertical plane, opstanding rocker arms carry their upper ends and ari ranged for pivotal action in planes transversely of said unbalanced shaft, and resilient support ing means engaging said screen frame at a point horizontally spaced from said vertical plane and von the side of said vertical plane opposite from said unbalanced shaft.

6, A vibratory screen "comprising, a screen framehaving a feed end and a discharge end 'elements supporting opposite Yopposed movement bodilytudinally odset from l vibratory frame and` provided with a longitudinally extending screen fabric, an unbalanced. shalt rotatably mounted on said screen frame in a transversely extending position and located approximately two-tliirds ci the way from the feed end to the discharge end of the screen fram the center of gravity of said screen trarne and unbalanced shaft lying in a vertical plane horizontally oiset from the center of rotation ci said unbalancedv shaft, a pair of universally resilient supporting side portions of said screen frame at points located near said vertical frame. a sub-frame, opstanding rocker armscarrying said supporting elementsattheir upper ends and pivotally 'mounted on said sub frame for movement in planes transversely of said unbalanced shaft, and resilient supporting elements mounted on, said sub-traine engaging and supporting said screen frame at points horizontally spaced from said vertical plane and on the side of said vertical plane opposite from said unbalanced shaft.

7. s. vibratory screen comprising a vibrator-y screen frame having a longitudinally extending screen fabric, a vibrator mounted on said screen frame, a stationary frame, resilient supports supportingly connected with the vibratory frame at points located approximately in a vertical plane passing, through the center of gravity of the screen frame and vibrator, means supporting said stationary frame and allowing said resilient supports substantially untudinal of the screen frame while restricting movement of the resilient supports bodily in a direction normal to the screen frame, and additional resilient supporting means mounted on said stationary frame and supporting said vibratory screen frame at a position horizontally spaced from said center of gravity in a direction longitudinally of the vibratory screen frame.

8.A vibratory screen comprising, a horizontally extending screen frame having a feed end and a discharge end and provided with a longitudinally extending screen fabric, an unbalanced gravity of said screen frame and unbalanced shaft lying in a transverse vertical plane longithe center of rotation of shaft, a. stationary frame, re supportingly connected with the at points located approximately in said transverse vertical plane, means supsiiient supports porting said resilient supports from the stationn ary frame and allowing said resilient supports substantially unopposed bodily -movementln s direction longitudinally of the screen trame while restricting bodily movement of the resilient supports in a direction normal to the screen frame,

and resilient supporting means mounted on said stationary frame engaging said screen frame at points longitudinally spaced from said transverse.

vertical plane plane which shaft. ,f

and at that -side of said vertical is opposite from'said unbalanced in a direction longi- 

